ES 2 110 902 A1 describes a length-measuring device of the above-mentioned type. The length-measuring device includes a hollow section member in which a scale tape extends, in a tensioned state, in the longitudinal direction. A mounting block is provided at each end of the scale tape, the scale tape being attached to each of the mounting blocks. The two mounting blocks are each positioned on the hollow section member by screws in such a way that the mounting blocks can be displaced relative to the hollow section. For purposes of position measurement, the scale tape is connected directly to a machine part by screwing the mounting blocks thereto, and thus temperature-induced changes in the length of the machine part are transferred to the scale tape. Since the mounting blocks are disposed on the hollow section member such that they are decoupled therefrom in the longitudinal direction, the hollow section member can thermally expand independently of the scale tape and, therefore, does not negatively affect the measuring accuracy of the length-measuring device.